I. Field of the Invention
The present invention relates to the determination of the homogeneity of one or more components of a mixture of powdered ingredients especially pharmaceuticals, and most importantly, the tabletted mixture of the powdered pharmaceutical mixture, including active and inactive ingredients. This invention is generally classified in USPTO Class 250, subclasses 343 and 339.12.
II. Description of the Prior Art
U.S. Pat. No. 4,640,614 to Roberts et al., issued Feb. 3, 1987, disclose a method and apparatus for testing of particulate material, particularly food products or the like. This patent uses near infrared reflectance spectrometry for analyzing the particulate material. With reference to FIG. 1, the apparatus analyzes a sample, either compacted or uncompacted, for a property such as protein, fat content, moisture and color, see column 1, line 13. However, there is no teaching or suggestion of a continuous sampling technique, using a library as a reference for sample materials or testing a mixture of products for homogeneity or purity.
U.S. Pat. No. 2,650,307 to Koppius issued Aug. 25, 1953, discloses an infrared analyzer for detecting a mixture of chemical compounds, particularly gaseous compounds. With reference to FIG. 1, the gaseous compounds are distilled in the column 11 and analyzed by an infrared analyzer using windows in the distillation column.
U.S. Pat. Nos. 5,187,368 to Galante et al., issued Feb. 16, 1993 and 4,975,581 to Robinson et al., issued Dec. 4, 1990 are concerned with infrared analyses of liquids such as biological fluids or drug products in sealed bags or vials. In the Galante et al., patent, the sensed near-infrared spectra is compared with a known spectra for product evaluation. The Robinson et al., patent also uses a model to facilitate analysis of the biological fluid sample. Neither of these patents are concerned with particulate material, granulates or mixtures and mixture homogeneity.
U.S. Pat, No. 5,305,076 to Inoue et al., issued Apr. 19, 1994, discloses a method and apparatus to determine the constituent ingredients in a sample using infrared methods. The teachings of this patent are particularly adapted for sample gases such as those in a vehicle exhaust, see column 2, lines 20-23. Ceilings or limit values are calculated and compared to the sensed value for sample analyses.
U.S. Pat. No. 5,233,715 to Taylor issued Jun. 29, 1993, discloses a process for obtaining spectral information and quantifying physical properties of a sample. This patent is also especially adapted for analyses of gases as demonstrated by the examples beginning in column 24. In this patent, a reference channel is used for sample analyses in conjunction with the sensed sample values.
Finally, U.S. Pat. No. 5,099,123 to Harjunmaa issued Mar. 24, 1992, discloses a method and apparatus for non-invasive testing of body fluids and tissues. In this patent, a zero baseline is derived from a patient to be tested for use in analyzing the body fluids or tissue. Near infrared radiation is used for sample analysis.
In summary, the prior an discussed above teaches that is it well known to use near infrared radiation to analyze various types of materials for their properties and/or concentrations. The Roberts et al., patent is particularly adapted for testing particulate material. However, this patent uses a static testing method and is not concerned with analyzing a mixture of particular materials, either prior to or after the mixture is compacted into a tablet.
The prior an also teaches that it is known to compare sensed values using near-infrared spectra to a known value for sample evaluation, see for example, the Galante et al., patent. However, this prior an does not teach or fairly suggest the features of the invention as described above, for example, measuring mixture homogeneity or purity using near-infrared radiation, particularly in a continuous fashion for tablet evaluation.